Aims and objectives: To investigate the assessment of psychosocial problems in children with type 1 diabetes by means of clinical estimations made by nurses and paediatricians and by using standardised questionnaires. Background: Although children with type 1 diabetes and their parents show increased risk for psychosocial problems, standardised assessment of these problems lacks in diabetes care. Design: By comparing these different modes of assessment, using a cross-sectional design, information about the additional value of using standardised questionnaires is provided. Methods: Participants were 110 children with type 1 diabetes (aged 4-16), their parents, and healthcare professionals. Children filled out the Strengths and Difficulties Questionnaire and the Paediatric Quality of Life Inventory, Diabetes Module. Parents filled out the Strengths and Difficulties Questionnaire parent-report and the Parenting Stress Index. Independently, nurses and paediatricians filled out a short questionnaire, which assessed their clinical estimations of the children’s psychosocial problems and quality of life, and parents’ levels of parenting stress. Reports of children and parents were compared to clinical estimations. Results: Children in our sample showed more psychosocial problems and lower health-related quality of life than their healthy peers. In approximately half of the children, dichotomous estimations by healthcare professionals and dichotomised reports by patients and parents were in agreement. In 10% of the children, no psychosocial problems were present according to professionals’ estimations, although patients and parents-reported psychosocial problems. In 40%, psychosocial problems were present according to professionals’ estimations, although parents and patients did not report psychosocial problems. Conclusion: Children with type 1 diabetes show more psychosocial problems than healthy children. Professionals seem to tend towards overestimating psychosocial problems. Relevance to clinical practice: Extending the assessment of psychosocial problems with routine screening on patient-reported outcomes, using validated questionnaires, could be of additional value in tailoring care to the needs of the individual child and parents.